Method for manufacturing liquid-cooled jacket

ABSTRACT

A liquid cooling jacket is produced by forming a first butted portion where a step side face of a peripheral wall portion and an outer peripheral side face of a sealing body butt each other and a third butted portion where a step side face of a support pillar portion and a hole wall of the hole portion of the sealing body portion butt each other with a gap, and friction-stirring by inserting a tip side pin and a base side pin of a primary joining rotary tool that is rotating into the sealing body and moving the primary joining rotary tool along the third butted portion with an outer circumferential face of the tip side pin being kept off the step side face while having a second aluminum alloy of the sealing body flow into the gap.

This application is a National Stage Application of PCT/JP2019/035959,filed Sep. 27, 2018, which claims benefit of priority to Japanese PatentApplication No. 2018-070623, filed Apr. 2, 2018, which applications areincorporated herein by reference. To the extent appropriate, a claim ofpriority is made to each of the above disclosed applications.

TECHNICAL FIELD

The present invention relates to a method for manufacturing aliquid-cooling jacket.

BACKGROUND ART

For instance, Patent Document 1 discloses a method for manufacturing aliquid-cooling jacket. FIG. 23 is a cross-sectional view of aconventional method for manufacturing a liquid-cooling jacket. Accordingto this conventional method for manufacturing the liquid-cooling jacket,friction-stir-welding is performed on an butted portion J10 at which astep side face 101 c formed at a step portion of a jacket body 101 of analuminum alloy and a side face 102 c of a sealing body 102 of analuminum alloy butt each other. In addition, the friction-stir-weldingis performed by inserting only a stirring pin F02 of a rotary tool F0into the butted portion J10. Furthermore, according to the conventionalmethod for manufacturing the liquid-cooling jacket, the rotary tool F10is moved in translation with a rotation center axis CL being alignedwith the butted portion J10.

CITATION LIST Patent Literature

Patent Document 1: JP2015-131321A

SUMMARY OF THE INVENTION Technical Problem

Since it is often the case that the jacket body 101 is in a complicatedshape, the jacket body 101 is made of a casting material such as a 4xxxaluminum alloy material while the sealing body 102 in a relativelysimple shape is made of a wrought aluminum material such as a 1xxxaluminum. Thus, a liquid-cooling jacket is often made by joining membersof different aluminum alloys. In a case like this, the jacket bodyusually has a higher hardness than the sealing body, and the stirringpin receives a higher material resistance from the jacket body 101 thanfrom the sealing body 102 while the friction-stir-welding is beingperformed, as shown in FIG. 23 . As a result, it is difficult to stirdifferent materials to mix them sufficiently with the stirring pin ofthe rotary tool F0, and there are cavity defects left in a plasticizedregion after the joining process, which results in a problem with alower strength of the joined portion.

In order to solve this problem, the present invention is intended toprovide a method for manufacturing a liquid-cooling jacket of members ofdifferent aluminum alloy materials that are appropriately joined in adesirable manner.

Solution to Problem

In order to achieve the objective above described, the present inventionprovides a feature of a method for manufacturing a liquid cooling jacketjoining a jacket body and a sealing body through friction-stirring,wherein the jacket body includes a bottom portion, a peripheral wallportion extending upward from a peripheral edge of the bottom portionand a support pillar extending upward from the bottom portion, and ismade of a first aluminum alloy, the sealing body includes a hole portioninto which a tip portion of the support pillar is inserted, seals anopening of the jacket body, and is made of a second aluminum alloy, thefirst aluminum alloy has a higher hardness than a hardness of the secondaluminum alloy, a rotary tool is a rotary tool for primary joining forthe friction stirring and includes a base side pin and a tip side pin,the base side pin has a taper angle larger than that of the tip sidepin, and the rotary tool includes a pin step portion formed in astaircase shape on an outer circumferential face of the base side pin,the method comprising a preparation process of forming a peripheral wallstep portion along an inner peripheral edge of the peripheral wallportion, the peripheral wall step portion including a step bottom faceand a step side face extending upward toward the opening of the jacketbody from the step bottom face and forming a support pillar step portionat the tip portion of the support pillar, the support pillar stepportion including a step bottom face and a step side face extendingdiagonally upward from the step bottom face in a way that the tipportion of the support pillar tapers to become thinner toward a tip endof the tip portion, wherein a plate thickness of the sealing body islarger than a height of the step side face of the support pillar stepportion, a placing process of placing the sealing body on the jacketbody to form a first butted portion, a second butted portion, a thirdbutted portion and a fourth butted portion, the first butted portionwhere the step side face of the peripheral wall step portion and anouter peripheral side face of the sealing body butt each other, thesecond butted portion where a back face of the sealing body is placed onthe step bottom face of the peripheral wall step portion, the thirdbutted portion where the step side face of the support pillar portionand a hole wall of the hole portion of the sealing body portion butteach other with a gap present between the step side face of the supportpillar portion and the hole wall, the fourth butted portion where theback face of the sealing body is placed on the step bottom face of thesupport pillar step bottom face, and a second primary joining process offriction-stirring being performed by inserting the tip side pin and thebase side pin of the rotary tool that is rotating into the sealing bodyand moving the rotary tool along the third butted portion with the outercircumferential face of the base side pin being in contact with a frontface of the sealing body and with an outer circumferential face of thetip side pin being kept off the step side face of the support pillarstep portion while having the second aluminum alloy of the sealing bodyflow into the gap.

According to the method above described for manufacturing a liquidcooling jacket, the second aluminum alloy, which is present on a side ofthe third butted portion where the sealing body is, is mainlyfriction-stirred with friction heat between the sealing body and boththe base side pin and the tip side pin, and plastically flows. As aresult, the step side face of the support pillar step portion and thehole wall of the hole portion of the sealing body can be joined togetherin the third butted portion. In addition, since friction-stirring isperformed with the base side pin and the tip side pin being in contactonly with the sealing body, the first aluminum alloy hardly mixes intothe sealing body from the jacket body. Accordingly, the second aluminumalloy is mainly friction-stirred in the third butted portion, whichsuppresses the strength of the joined portion decreasing. In addition,since the step side face of the support pillar step portion tapers tobecome thinner towards its tip, both the base side pin and the tip sidepin can be easily prevented from coming in contact with the jacket bodywithout decreasing the strength of the joined portion. In addition,since a thickness of the sealing body is increased to have theplastically flowing material sufficiently flow into the gap in the thirdbutted portion, the joined portion can be prevented from being short ofmetal.

In addition, the friction-stirring in the second primary joining processas described above is performed preferably by moving the rotary toolalong the third butted portion with the tip side pin being slightly incontact with the step bottom face of the support pillar step portion.

According to this method, the strength of the joined fourth buttedportion can be increased.

In addition, the present invention provides a feature of a method formanufacturing a liquid cooling jacket joining a jacket body and asealing body through friction-stirring, wherein the jacket body includesa bottom portion, a peripheral wall portion extending upward from aperipheral edge of the bottom portion and a support pillar extendingupward from the bottom portion, and is made of a first aluminum alloy,the sealing body includes a hole portion into which a tip portion of thesupport pillar is inserted, seals an opening of the jacket body and ismade of a second aluminum alloy, the first aluminum alloy has a higherhardness than a hardness of the second aluminum alloy, a rotary tool isa rotary tool for primary joining for the friction stirring and includesa base side pin and a tip side pin, the base side pin has a taper anglelarger than that of the tip side pin, and the rotary tool includes a pinstep portion formed in a staircase shape on an outer circumferentialface of the base side pin, the method comprising a preparation processof forming a peripheral wall step portion along an inner peripheral edgeof the peripheral wall portion, the peripheral wall step portionincluding a step bottom face and a step side face extending upwardtoward the opening of the jacket body from the step bottom face andforming a support pillar step portion at the tip portion of the supportpillar, the support pillar step portion including a step bottom face anda step side face extending diagonally upward from the step bottom facein a way that the tip portion of the support pillar tapers to becomethinner toward a tip end of the tip portion, wherein a plate thicknessof the sealing body is larger than a height of the step side face of thesupport pillar step portion, a placing process of placing the sealingbody on the jacket body to form a first butted portion, a second buttedportion, a third butted portion and a fourth butted portion, the firstbutted portion where the step side face of the peripheral wall portionand an outer peripheral side face of the sealing body butt each other,the second butted portion where a back face of the sealing body isplaced on the step bottom face of the peripheral wall step portion, thethird butted portion where the step side face of the support pillarportion and a hole wall of the hole portion of the sealing body portionbutt each other with a gap present between the step side face of thesupport pillar portion and the hole wall, the fourth butted portionwhere the back face of the sealing body is placed on the step bottomface of the support pillar step bottom face and a second primary joiningprocess of friction-stirring being performed by inserting the tip sidepin and the base side pin of the rotary tool that is rotating into thesealing body and moving the rotary tool along the third butted portionwith the outer circumferential face of the base side pin being incontact with a front face of the sealing body and with an outercircumferential face of the tip side pin being slightly in contact withthe step side face of the support pillar step portion while having thesecond aluminum alloy of the sealing body flow into the gap.

According to the method for manufacturing a liquid cooling jacket, thesecond aluminum alloy, which is present on a side of the third buttedportion where the sealing body is, is mainly friction-stirred withfriction heat between the sealing body and both the base side pin andthe tip side pin, and plastically flows. As a result, the step side faceof the support pillar step portion and the hole wall of the hole portionof the sealing body can be joined together in the third butted portion.In addition, since friction-stirring is performed with an outercircumferential face of the tip side pin being only slightly in contactwith the step side face of the support pillar step portion, an amount ofthe first aluminum mixing into the sealing body from the jacket body canbe kept very small.

In addition, since the step side face of the support pillar step portioninclines tapering to become thinner towards its tip, the third buttedportion is joined without a large portion of the tip side pin cominginto the jacket body. In addition, since a thickness of the sealing bodyis increased to have the plastically flowing material sufficiently flowinto the gap in the third butted portion, the joined portion can beprevented from being short of metal.

In addition, the friction-stirring in the second primary joining processas described above is performed preferably by moving the rotary toolalong the third butted portion with the tip side pin being slightly incontact with the step bottom face of the support pillar step portion.

According to this method, the strength of the joined fourth buttedportion can be increased.

In addition, the friction-stirring in the second primary joining processabove described is performed preferably by moving the rotary tool alongthe third butted portion and making one round around the support pillarstep portion.

This method as described can improve a water-tightness property and agas-tightness property of the liquid cooling jacket.

In addition, the method above described preferably comprises further afirst primary joining process of friction-stirring on the first buttedportion by moving the rotary tool one round along the first buttedportion.

This method as described can improve a water-tightness property and agas-tightness property of the liquid cooling jacket.

In addition, the preparation process preferably includes the followingsteps of the jacket body being formed through die-casting, the bottomportion of the jacket body being formed in a raised shape with a frontface of the bottom portion being raised, and the sealing body beingformed in a raised shape with a front face of the sealing body beingraised.

The sealing body of the liquid cooling jacket can deform to be in arecessed shape due to its thermal contraction caused by the heat to beconducted to the plasticized zone through friction-stir-welding.However, according to this method, both the jacket body and the sealingbody are deformed to be in a raised shape in advance of joining and theliquid cooling jacket can be made flat by the thermal contraction.

In addition, preferably, a deformation amount of the jacket body ismeasured in advance and the friction-stirring is performed while aninsertion depth of the base side pin and the tip side pin of the rotarytool is being adjusted in accordance with the deformation amount in thefirst primary joining process.

According to this method, the plasticized zone formed in the liquidcooling jacket can have a uniform depth and a uniform width, whenfriction-stir-welding is performed with both the jacket body and thesealing body deformed in a raised shape.

In addition, a provisional joining process to provisionally join thefirst butted portion is preferably performed prior to the first primaryjoining process.

The method as described including the provisional joining process canprevent a gap from being formed at the first butted portion.

In addition, preferably a cooling plate in which a cooling medium flowsis fixed on a back face of the bottom portion and the friction-stirringis performed while the jacket body and the sealing body are being cooledby the cooling plate, in the first primary joining process.

The method as described can dissipate friction heat and decreasedeformation of the liquid cooling jacket to be caused by the thermalcontraction.

In addition, a front face of the cooling plate is preferably made to bein face-contact with the back face of the bottom portion. This methodcan enhance cooling efficiency.

In addition, the cooling plate includes preferably a cooling passagethrough which the cooling medium flows and the cooling passage, and thecooling passage has a planar shape that corresponds to a moving trackalong which the rotary tool moves in the first primary joining process.

Since the method as described enables intensively cooling the portionthat is being friction-stirred, the cooling efficiency is furtherenhanced.

In addition, the cooling passage through which the cooling medium flowsis constituted preferably by a cooling pipe that is embedded in thecooling plate.

The method as described enables easily controlling the cooling medium.

In addition, in the first primary joining process, the friction-stirringis preferably performed while the jacket body and the sealing body arebeing cooled by a cooling medium being made to flow in a hollow portionformed by the jacket body and the sealing body.

The method as described enables dissipating the friction heat and makingsmall the deformation of the liquid cooling jacket caused by thermalcontraction. The cooling is performed by using the jacket body withoutusing the cooling plate and the like.

Advantageous Effects of the Invention

The method for manufacturing a liquid-cooling jacket of the presentinvention enables joining different aluminum alloys in a desirablemanner.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side elevation view of a primary joining rotary tool of anembodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the primary joining rotarytool.

FIG. 3 is a cross sectional view of a rotary tool of a firstmodification example used for the primary joining.

FIG. 4 is a cross sectional view of a rotary tool of a secondmodification example used for the primary joining.

FIG. 5 is a cross sectional view of a rotary tool of a thirdmodification example used for the primary joining.

FIG. 6 is a perspective exploded view of a liquid-cooling jacket of thefirst embodiment of the present invention.

FIG. 7 is a cross-sectional view of a placing process of a method formanufacturing the liquid-cooling jacket of the first embodiment of thepresent invention.

FIG. 8 is a perspective view of a first primary joining process of themethod for manufacturing a liquid-cooling jacket of the first embodimentof the present invention.

FIG. 9 is a cross-sectional view of the first primary joining process ofthe method for manufacturing a liquid-cooling jacket of the firstembodiment of the present invention.

FIG. 10 is a cross-sectional view of joined members after the firstprimary joining process of the method for manufacturing a liquid-coolingjacket of the first embodiment of the present invention.

FIG. 11 is a perspective view of a second primary joining process of themethod for manufacturing a liquid-cooling jacket of the first embodimentof the present invention.

FIG. 12 is a cross-sectional view of the second primary joining processof the method for manufacturing a liquid-cooling jacket of the firstembodiment of the present invention.

FIG. 13 schematically shows a conventional rotary tool.

FIG. 14 schematically shows a conventional rotary tool.

FIG. 15 is a cross-sectional view of a first primary joining process ofa method for manufacturing a liquid-cooling jacket of a secondembodiment of the present invention.

FIG. 16 is a cross-sectional view of a first primary joining process ofa method for manufacturing a liquid-cooling jacket of a third embodimentof the present invention.

FIG. 17 is a cross-sectional view of a first primary joining process ofa method for manufacturing a liquid-cooling jacket of a fourthembodiment of the present invention.

FIG. 18 is a cross-sectional view of a first primary joining process ofa method for manufacturing a liquid-cooling jacket of a fifth embodimentof the present invention.

FIG. 19 is a perspective view of a first modification example of amethod for manufacturing a liquid-cooling jacket of the first embodimentof the present invention.

FIG. 20A shows a second modification example of a method formanufacturing a liquid-cooling jacket of the first embodiment of thepresent invention and is a perspective view of a table.

FIG. 20B shows the second modification example of the method formanufacturing a liquid-cooling process of the first embodiment of thepresent invention and is a perspective view of a jacket body and asealing body that are clamped to the table.

FIG. 21 is a perspective exploded view of a third example of a methodfor manufacturing a liquid-cooling jacket of the first embodiment of thepresent invention.

FIG. 22 shows the third example of the method for manufacturing aliquid-cooling jacket of the first embodiment of the present inventionand is a perspective view of a jacket body and a sealing body beingclamped to a table.

FIG. 23 is a cross-sectional view of a conventional method formanufacturing a liquid-cooling-jacket.

DESCRIPTION OF EMBODIMENTS

An embodiment of the present invention is described appropriately withreference to the drawings. To begin with, a primary joining rotary tool(rotary tool) used for a joining method of this embodiment is described.The primary joining rotary tool is intended to be used forfriction-stir-welding. As shown in FIG. 1 , the primary joining rotarytool F is made of, for example, tool steel and consists mainly of a baseshaft portion F1, a base side pin F2 and a tip side pin F3. The baseshaft pin F1 is in a columnar shape and connected with a main shaft of afriction stir welding apparatus.

The base side pin F2 is formed to extend from the base shaft portion F1and tapers to be thinner toward its tip side. The base side pin F2 is ina conical shape with its tip portion cut off. The base side pin F2 has ataper angle A that may be appropriately set, for example, to between135° and 160°. If the taper angle A is smaller than 135° or larger than160°, a joined surface after friction-stirring has a surface roughnessthat is relatively large. This taper angle A is set to be larger than ataper angle B of the tip side pin F3, which is described later. As shownin FIG. 2 , a pin step portion F21 in a staircase shape is formed on anouter circumferential face of the base side pin F2 wholly in its heightdirection. The pin step portion F21 is formed in a clockwise orcounterclockwise spiral shape. That is, the pin step portion F21 is in aspiral shape in its plane view and in a staircase shape in its sideview. Since the primary joining rotary tool F is rotated clockwise forthis embodiment, the pin step portion F21 is formed in the clockwiseshape from a base side to a tip side of the base side pin F2.

If the primary joining rotary tool F rotates counterclockwise, the pinstep portion is preferably formed clockwise from the base side to thetip side. This enables reducing an amount of metal coming out of themetal member to be joined, because the plastically flowing material isled toward the tip side of the base side pin F2 by the pin step portionF21. The pin step portion F21 is formed by a step bottom face F21 a anda step side face F21 b. A distance X1 (horizontal direction distance)between adjacent apexes F21 c, F21 c on the pin step portion 21 isappropriately set based on a step angle C and a height Y1 of the stepside face F21 b, which are described later.

The height Y1 of the step side face F21 b may be preferably set, forexample, to between 0.1 and 0.4 mm. If the height Y1 is less than 0.1mm, the joined surface has a relatively large surface roughness. On theother hand, if the height Y1 is more than 0.4 mm, the joined surfacetends to have a relatively large surface roughness and the number ofeffective steps (number of steps of the pin step portion F21 in contactwith the metal member to be joined) becomes fewer.

The step angle C made between the step bottom face F21 a and the stepside face F21 b may appropriately set and, for example, set to between85° and 120°. The step bottom face F21 a in this embodiment is inparallel with a horizontal plane. The step bottom face F21 a may beinclined by between −5° and 15° relative to the horizontal plane from arotation axis of the rotary tool toward its outer circumference (a minusangle corresponds to the step bottom face F21 a extending outwardinclining downward relative to the horizontal plane and a plus anglecorresponds to the step bottom face F21 a extending outward incliningupward relative to the horizontal plane). The distance X1, the height Y1of the step side face F21 b, the step angle C and the angle of the stepbottom face F21 a relative to the horizontal plane are set in a mannerthat the plastically flowing material flows out of the pin step portionF21 without being stuck in and adhering to the pin step portion F21 andis sufficiently held down by the step bottom face F21 a for the joinedsurface to have a relatively small surface roughness.

As shown in FIG. 1 , the tip side pin F3 is formed to extendcontinuously from the base side pin F2. The tip side pin F3 is in aconical shape with its tip portion cut off. The tip side pin F3 has aflat face F4 that is formed on its tip portion and is perpendicular tothe rotation axis. The tip side pin F3 has a taper angle B that issmaller than the taper angle A of the base side pin F2. As shown in FIG.2 , a spiral groove F31 is engraved on an outer circumferential face ofthe tip side pin F3. The spiral groove F31 may be formed clockwise orcounterclockwise. Since the primary joining rotary tool F is rotatedclockwise in this embodiment, the spiral groove is engravedcounterclockwise from a base side to a tip side of the tip side pin F3.

If the primary joining rotary tool F is rotated counterclockwise, thespiral groove F31 is preferably formed clockwise from the base side tothe tip side of the tip side pin F3. This enables reducing an amount ofmetal coming out of the metal member to be joined, because theplastically flowing material is led toward the tip side of the tip sidepin F3 by the spiral groove F31. The spiral groove F31 is formed by aspiral bottom face F31 a and a spiral side face F31 b. A distance X2denotes a distance (horizontal direction distance) between adjacentapexes F31 c, F31 c on a pin step portion. A height Y2 denotes a heightof the spiral side face F31 b. A spiral angle D made between the spiralbottom face F31 a and the spiral side face F31 b may be formed, forexample, to be between 45° and 90°. The spiral groove F31 is intended tofunction for increasing friction heat by contacting a metal member to bejoined and leading the plastically flowing material toward the tip side.

The configuration of the primary joining rotary tool F may beappropriately modified. FIG. 3 is a side elevation view of a firstmodification example of the rotary tool of the present invention. Asshown in FIG. 3 , a primary joining rotary tool FA of the firstmodification example has the step angle C between the step bottom faceF21 a of the pin step portion F21 and the pin step side face F21 b ofthe pin step portion F21 being equal to 85°. The step bottom face 21 ais in parallel with the horizontal plane. Thus, the step angle C may beset to such an acute angle that the plastically flowing material is ableto come out of the pin step portion F21 without being stuck in andadhering to the pin step portion F21 while friction-stirring is beingperformed, if the step bottom face F21 a is in parallel with thehorizontal plane.

FIG. 4 is a side elevation view of a second modification example of theprimary joining rotary tool of the present invention. As shown in FIG. 4, a primary joining rotary tool FB of the second modification examplehas the step angle C of the pin step portion F21 being equal to 115°.The step bottom face F21 a is in parallel with the horizontal plane.Thus, the step angle C may be set to an obtuse angle as long as the pinstep portion F21 functions as intended, if the step bottom face F21 a isin parallel with the horizontal plane.

FIG. 5 is a side elevation view of a third modification example of theprimary joining rotary tool of the present invention. As shown in FIG. 5, a primary joining rotary tool FC has the step bottom face F21 aextending from a rotation axis side toward an outer periphery incliningupward at 10° to the horizontal plane. The step side face F21 b is inparallel with a vertical plane. Thus, the step bottom face F21 a may beformed to incline upward relative to the horizontal plane from therotation axis side toward an outer circumference so that the plasticallyflowing material is held down while friction-stirring is beingperformed. If any of the primary joining tools of the first to thirdmodification examples above mentioned is used, an equivalent effect tothat for the embodiments described below is obtained.

First Embodiment

The method for manufacturing a liquid-cooling jacket of the presentinvention is described in detail with reference to the drawings. Asshown in FIG. 6 , the method for manufacturing a liquid-cooling jacket 1of this embodiment is intended to manufacture a liquid-cooling jacket 1by friction-stir-welding on a sealing body 3 and a jacket body 2. Theliquid-cooling jacket 1 is a device inside which liquid flows and towhich heat is transferred from a heat generating body member (not shown)mounted on the sealing body 3. In the description below, “front face”means an opposite face of “back face”.

In the method for manufacturing a liquid-cooling jacket of thisembodiment, a preparation process, a placing process, a first primaryjoining process and a second primary joining process are performed. Thepreparation process is a process in which the jacket body 2 and thesealing body 3 are prepared. The jacket body 2 includes a bottom portion10, a peripheral wall portion 11 and plural support pillars 15. Thejacket body 2 is made mainly of a first aluminum alloy. The firstaluminum alloy is, for example, an aluminum alloy for casting such asJIS H5302 ADC12 (Al—Si—Cu system).

The bottom portion 10 is a plate-like portion in a rectangular shape ina plan view. The peripheral wall portion 11 is a wall portion extendingupward from a peripheral edge of the wall portion 10 to be in arectangular frame shape. A recessed portion 13 is formed of the bottomportion 10 and the peripheral wall portion 11. A peripheral wall stepportion 12 is formed along an inner peripheral edge of the peripheralbottom portion 11. The peripheral wall step portion 12 is formed by astep bottom face 12 a and a step side face 12 b extending upward fromthe step bottom face 12 a. As shown in FIG. 7 , the step side face 12 bextends upward from the step bottom face 12 a toward an opening of thejacket body 2 inclining outward. An inclination angle ß may beappropriately set and is, for example, between 3° and 30° relative tothe vertical plane. Then, the step side face 12 b may be perpendicularto step bottom face 12 a.

As shown in FIG. 6 , the support pillars 15 extend vertically from thebottom portion 10. There is no limitation on the number of the supportpillars 15, and four support pillars 15 are formed in this embodiment.The support pillars 15 are in a columnar shape in this embodiment andmay be in any different shape. A protruding portion 16, which has acircular truncated cone shape, is formed at a top portion of each of thesupport pillar 15. As a result of the protruding portion 16 being formedon an end face of the support pillar, a support pillar step portion 17is formed. The support pillar step portion 17 is formed by a step bottomface 17 a and a step side face 17 b extending upward from the stepbottom face 17 a. The step side face 17 b has such an inclination thatthe step side face 17 b inclines tapering to be thinner towards a tip ofthe support pillar 15. An inclination angle δ of the step side face 17 bmay be appropriately set and is set, for example, to between 3 and 30degrees relative to the vertical plane in this embodiment.

As shown in FIG. 7 , the step bottom face 17 a of the support pillarstep portion 17 is formed at the same height as the step bottom face 12a of the peripheral wall step portion 12. The end face 16 a of theprotruding portion 16 is formed to be at the same height as the 11 a ofthe 11. The jacket body 2 may be formed by the bottom portion 10 and theouter peripheral portion 11 which are separate from each other andjoined together with a seal member.

As shown in FIG. 6 , the sealing body 3 is a plate-like member to closethe opening of the jacket body 2. The sealing body 3 is sized to beplaced on the peripheral wall step portion 12. The sealing body 3 has aplate thickness that is larger than a height of the step side face 12 b.The sealing body 3 is made mainly of a second aluminum alloy. The secondaluminum alloy is a material having a hardness that is lower than thefirst aluminum alloy has. The second aluminum alloy may be an aluminumexpanded material such as JIS A1050, A1100 or A6063. A thickness of thesealing body 3 may be appropriately set so that a joined portion is notshort of metal after a first primary joining process to be describedlater.

There are plural hole portions 4 formed through the sealing body 3. Thehole portions 4 are formed at positions respectively corresponding tothe protruding portion 16 of the support pillars 15. Each of the holeportions 4 has a hollow portion in a columnar shape and has such a sizethat the protruding portion 16 is inserted therein.

The placing process is a process to place the sealing body 3 on thejacket body 2, as shown in FIG. 7 . In the placing process, a back face3 b of the sealing body 3 is placed on the step bottom face 12 a. As aresult, the step side face 12 b and an outer peripheral side face 3 c ofthe sealing body 3 butt each other to form a first butted portion J1.The first butted portion J1 may be a portion where the step side face 12b and the outer peripheral side face 3 c of the sealing body 3 are inface-contact with each other, or may be a portion where the step sideface 12 b and the outer peripheral side face 3 c of the sealing body 3butt each other with a gap present therebetween that is seenapproximately in a wedge shape in a cross-sectional view as described inthe present embodiment. A second butted portion J2 is formed by the stepbottom face 12 a and a back face 3 b of the sealing body 3 that are madeto butt each other.

In addition, a third butted portion J3 is formed by the step side face17 b of the support pillar step portion 17 and a hole wall 4 a of thehole portion 4 that are made to butt each other. The third buttedportion J3 may be an butted portion with a gap seen approximately in awedge shape in a cross section of the third butted portion J3. Inaddition, a fourth butted portion J4 is formed by the back face 3 b ofthe sealing body 3 and the step bottom face 17 a of the support pillarstep portion 17 which are made to butt each other.

The first primary joining process is a process to friction-stir-weld onthe first butted portion J1 with the primary joining rotary tool F, asshown in FIG. 8 . In the first primary joining process, the primaryjoining rotary tool F that is rotating clockwise is inserted at astarting position Sp predetermined on a front face 3 a of the sealingbody 3 and is moved in translation clockwise along the periphery of thesealing body 3 while having a plastically flowing material flow into thegap in the first butted portion J1. A plasticized region W1 is formed ofmetal that has been friction-stirred and hardened along a moving trackalong which the primary joining rotary tool F has moved.

As shown in FIG. 9 , friction-stirring is performed in the first primaryjoining process with both the base side pin F2 and the tip side pin F3being in contact with the sealing body 3 and with both the base side pinF2 and the tip side pin F3 being kept off the step side face 12 b. Aninsertion depth of the primary joining rotary tool F is set to such adepth that friction-stirring is performed with an outer circumferentialface of the base side pin F2 being in contact with a front face 3 a ofthe sealing body 3 and with the tip side pin F3 being kept off and abovethe step bottom face 12 a. Furthermore, the outer circumferential faceof the base side pin F2 is kept off the 11 a. The state in which theouter circumferential face of the tip side pin F3 is kept off the jacketbody 2 may be a state in which a distance between the tip side pin F3and the step side face 12 b is zero.

If the distance from the step side face 12 b to the outercircumferential face of the tip side pin F3 is too large, the strengthof the joined first butted portion J1 decreases. A separation distance Lfrom the step side face 12 b to the outer circumferential face of thetip side pin F3 may be appropriately set based on the materials of thejacket body 2 and the sealing body 3, and may be set to 0≤L≤0.5 mm, andis preferably 0≤L≤0.3 mm, if the outer circumferential face of the tipside pin F3 is kept off the step side face 12 b and the flat face F4 ofthe tip side pin F3 is kept off and above the step bottom face 12 a, asis the case with the present embodiment.

After the primary joining rotary tool F is made to move one round alongthe outer periphery of the sealing body 3, the primary joining rotarytool F is stopped at the position in the plasticized region W1 fromwhich the primary joining rotary tool F started to move in translation.Then, the primary joining rotary tool F may be lifted gradually upwardand pulled out of the front face 3 a of the sealing body 3. FIG. 10shows a cross-sectional view of the joined portion after the firstprimary joining process of the present embodiment. The plasticizedregion W1 borders the first butted portion J1 and is formed on a side ofthe first butted portion J1 where the sealing body 3 is.

As shown in FIG. 11 and FIG. 12 , the second primary joining process isa process to friction-stir-weld on the third butted portion J3 with theprimary joining rotary tool F. In the second primary joining process asshown in FIG. 11 , the base side pin F2 and the tip side pin F3 that arerotating clockwise is inserted at a start position predetermined on thefront face 3 a of the sealing body 3 and moved one round along the holewall 4 a of the hole portion 4 while the plastically flowing material isbeing made to flow into the gap in the third butted portion J3. Theplasticized zone W2 is formed along a track along which the primaryjoining rotary tool F has moved after the friction-stirred metalhardens.

As shown in FIG. 12 , friction-stirring is performed in the secondprimary joining process with both the base side pin F2 and the tip sidepin F3 being in contact with the sealing body 3 and with both the baseside pin F2 and the tip side pin F3 being not in contact with the stepside face 17 b. In addition, the insertion depth of the primary joiningrotary tool F is kept at such a depth that friction-stirring isperformed with the outer circumferential face of the base side pin F2being in contact with the front face 3 a of the sealing body 3 and withthe tip side pin F3 being not in contact with the step bottom face 17 a.In addition, the outer circumferential face of the base side pin F2 iskept off the end face 16 a of the protruding portion 16. The state inwhich the tip side pin F3 is kept off the protruding portion 16 may be astate in which a distance between the tip side pin F3 and the step sideface 17 b is zero.

After the primary joining tool F is moved one round around the holeportion 4, the primary joining rotary tool F is stopped at a position inthe plasticized region W2 from which the primary joining rotary tool Fstarted to move in translation. Then, the primary joining rotary tool Fmay be lifted gradually upward and pulled out of the front face 3 a ofthe sealing body 3. A separation distance L from the step side face 17 bof the support pillar step portion 17 to the outer circumferential faceof the tip side pin F3 may be set in the same way as in the firstprimary joining process.

According to the method for manufacturing the liquid-cooling jacket ofthis embodiment as has been described, the second aluminum alloy on aside of the first butted portion J1, where the sealing body 3 is, ismainly friction-stirred to flow plastically by friction heat between thesealing body 3 and both the base side pin F2 and the tip side pin F3,and thus the step side face 12 b and the outer peripheral side face 3 cof the sealing body 3 can be joined together at the first butted portionJ1. In addition, since friction-stirring is performed with both the baseside pin F2 and the tip side pin F3 being in contact only with thesealing body 3, the first aluminum alloy of the jacket body 2 hardlymixes into the sealing body 3. Accordingly, since the second aluminumalloy of the sealing body 3 is mainly friction-stirred at the firstbutted portion J1, the strength of the joined portion is prevented fromdecreasing. In addition, the step side face 12 b of the jacket body 2 isformed to incline outward toward the opening of the jacket body 2, boththe base side pin F2 and the tip side pin F3 are easily prevented fromcoming into contact with the jacket body 2 without decreasing thestrength of the joined portion. In addition, since the thickness of thesealing body 3 is increased and the plastically flowing material is madeto flow into the gap in the first butted portion J1, the joined portioncan be prevented from being short of metal.

If the conventional rotary tool 900 as shown in FIG. 13 is used, themetal member 910 to be joined is not held down by the shoulder portion,which results in problems with a recessed groove (formed by the frontface of the metal member to be joined and a surface of the plasticizedregion) becoming larger and a surface roughness of the joined facebecoming larger. In addition, there would be a problem that a raisedportion (portion of joined metal members having a front face raised fromthe front face of the joined metal members before joining) could beformed on the side of the recessed groove. On the other hand, if arotary tool 901 as shown in FIG. 14 , which has a taper angle E2 beinglarger than the taper angle E1 of the rotary tool 900, is used, therecessed groove would be made smaller and the raised portion is madesmaller as well, because the front face of the metal member to be joinedcan be more strongly held down than the rotary tool 900. However,downward plasticized material flow would be so strong that a kissingbond is more likely to be formed under the plasticized region.

To the contrary, the primary joining rotary tool F of the presentembodiment includes the base side pin F2 and the tip side pin F3 havingthe taper angle B smaller than the taper angle A of the base side pinF2. Due to this configuration, the primary joining rotary tool F can beeasily inserted into the sealing body 3. In addition, since the taperangle B of the tip side pin F3 is smaller, the primary joining rotarytool F can be easily inserted to a deep position in the sealing body 3.In addition, due to the taper angle B of the tip side pin F3 beingsmaller, the plasticized material flowing downward is suppressed,compared with the rotary tool 901. Accordingly, a kissing bond can beprevented from being formed under the plasticized region W1. On theother hand, since the taper angle A of the base side pin F2 is larger,joining is more reliably performed with this rotary tool than with theconventional rotary tool, even if the thickness of the metal member tobe joined varies or the height position of the joining varies.

In addition, since the plastically flowing material can be held down bythe outer circumferential face of the base side pin F2, the recessedgroove formed on the joined face can be made smaller and the raisedportion that can be formed on the side of the recessed groove is notformed or made smaller if it is formed. In addition, since the pin stepportion F21 is relatively shallow and has a wide exit, the plasticallyflowing material can easily flow out of the pin step portion F21 thoughthe plastically flowing material is held down by the step bottom faceF21 a. As a result, the plastically flowing material is hardly stuck onthe outer circumferential face of the base side pin F2, though theplastically flowing material is held down by the base side pin F2.Accordingly, the surface roughness of the joined portion is made smallerand the joining quality is preferably stabilized.

In addition, since the step side face 12 b of the jacket body 2 inclinesoutward toward the opening of the jacket body 2 in the first primaryjoining process, the tip side pin F3 can be easily prevented from comingin contact with the jacket body 2. In addition, since the inclinationangle ß of the step side face 12 b (See FIG. 7 ) is equal to theinclination angle α (See FIG. 1 ) of the tip side pin F3 (the step sideface 12 b is in parallel with the outer circumferential face of the tipside pin F3) in the present embodiment, the tip side pin F3 can bepositioned very close to the step side face 12 b, while the tip side pinF3 is prevented from coming in contact with the step side face 12 b.

In addition, although the rotation direction and the moving direction ofthe primary joining rotary tool F can be appropriately determined in thefirst primary joining process, the rotation direction and the movingdirection of the primary joining rotary tool F are set in a manner thatthe jacket body 2 is positioned on a shear side of the plasticizedregion W1 formed along a moving track along which the primary joiningrotary tool F has moved while the sealing body 3 is positioned on a flowside of the plasticized region W1. Since the jacket body portion 2 ispositioned on the shear side, the stirring action by the base side pinF2 and the tip side pin F3 is enhanced in the vicinity of the firstbutted portion J1, the temperature at the first butted portion J1presumably becomes higher, which contributes to more reliably joiningthe step side face 12 b and the outer peripheral side face 3 c of thesealing body 3 at the first butted portion J1.

The shear side (advancing side) refers to a side where a relativevelocity of the rotary tool at its circumference relative to a portionto be joined is a summation of a tangential velocity of the rotary tooland a moving velocity of the rotary tool. On the other hand, the flowside (retreating side) refers to a side where the rotary tool is rotatedto move in an opposite direction to the moving direction in which therotary tool is moved. Thus, the relative velocity of the rotary tool atits circumference relative to a portion to be joined is lower.

In addition, performing the second primary joining process can increasethe joining strength between the jacket body 2 and the sealing body 3.

In addition, friction-stirring is performed with both the base side pinF2 and the tip side pin F3 kept off the step side face 17 b of thesupport pillar step portion 17 in the second primary joining process aswell. As a result, the second aluminum alloy, which is present on a sideof the third butted portion J3, where the sealing body 3 is, is mainlyfriction-stirred and made to plastically flow due to friction heatbetween the sealing body 3 and both the base side pin F2 and the tipside pin F3, and the step side face 17 b of the support pillar stepportion 17 and the hole wall 4 a of the hole portion 4 of the sealingbody 3 can be joined together at the third butted portion J3.

In addition, since the friction-stirring is performed with both the baseside pin F2 and the tip side pin F3 being in contact only with thesealing body 3, the first aluminum alloy hardly mixes into the sealingbody 3 from the jacket body 2. As a result, the second aluminum alloy ofthe sealing body 3 is mainly friction-stirred at the third buttedportion J3, which enables suppressing a decrease in the strength of thejoined portion. In addition, since the step side face 17 b of thesupport pillar step portion 17 inclines tapering to become thinnertowards its tip, it is possible to easily avoid both the base side pinF2 and the tip side pin F3 coming in contact with the jacket body 2without decreasing the joining strength. In addition, the thickness ofthe sealing body 3 is larger to have the plastically flowing materialflow into the gap at the third butted portion J3, which enablespreventing the joined portion from being short of metal.

In addition, the step side face 17 b of the support pillar step portion17 inclines tapering to become thinner toward its tip, which enableseasily preventing the tip side pin F3 from coming in contact with thesupport pillar 15 of the jacket body 2. In addition, since theinclination angle δ of the step side face 17 b (as seen in FIG. 7 ) isset to be equal to the inclination angle α of the tip side pin F3 (asseen in FIG. 1 , then the step side face 17 b is in parallel with theouter circumferential face of the tip side pin F3), the tip side pin F3can be positioned very close to the step side face 17 b though the tipside pin 3 is kept off the step side face 17 b.

In the second primary joining process, friction-stirring may beperformed with both the base side pin F2 and the tip side pin F3 beingkept off the step side face 17 b and with the flat face F4 of the tipside pin F3 being in contact with the step bottom face 17 a of thesupport pillar step portion 17, which results in an increase in thejoining strength at the fourth butted portion.

In addition, since the thickness of the sealing body 3 is set to belarger than the height of the step side face 12 b, it is possible toprevent the first butted portion J1 and the third butted portion J3 frombeing short of metal. In addition, the sealing body 3 having a largerthickness contributes to making the heat dissipation more efficient,compared with the sealing body 3 having a smaller thickness.

In addition, since the first aluminum alloy of the jacket body 2 has ahardness higher than that of the second aluminum alloy of the sealingbody 3, durability of the liquid-cooling jacket 1 is improved. The firstaluminum alloy of the jacket body 2 is preferably a cast aluminum alloyand the second aluminum alloy of the sealing body 3 is preferably awrought aluminum alloy. For example, if an Al—Si—Cu system aluminumalloy casting material such as JIS H5302 ADC 12 is used for the firstaluminum alloy, the jacket body 2 has good castability, high strengthand cutting property. In addition, if JIS A1xxx aluminum or JIS A6xxxaluminum alloy is used for the second aluminum alloy, the secondaluminum alloy has good workability and high thermal conductivity.

In addition, any one of the first primary joining process and the secondprimary joining process may be performed prior to the other primaryjoining process. Furthermore, a provisional joining throughfriction-stirring or welding may be performed on the first buttedportion J1 prior to the first primary joining process. If theprovisional joining is performed, a gap can be prevented from beingformed in the butted portion when each of the first primary joiningprocess and the second primary joining process is performed.

Second Embodiment

Next, a method for manufacturing a liquid-cooling jacket of a secondembodiment of the present invention is described. A preparation process,a placing process, a first primary joining process and a second primaryjoining process are performed for the method for manufacturing aliquid-cooling jacket of the second embodiment. The preparation process,the placing process and the second primary joining process in the secondembodiment are equivalent to corresponding processes in the firstembodiment. Accordingly, no explanation on these processes is repeated.The following description focusses on differences from the firstembodiment.

As shown in FIG. 15 , when the primary joining rotary tool F moves alongthe first butted portion J1 in the first primary joining process,friction-stirring is performed with the tip side pin F3 being positionedto have a small portion of the tip side pin F3 disposed across the stepside face 12 b and with the outer circumferential face of the base sidepin F2 being in contact with the front face 3 a of the sealing body 3.In the first primary joining process, the outer circumferential face ofthe base side pin F2 is not in contact with the peripheral wall end face11 a, and the tip side pin F3 is not in contact with the step bottomface 12 a.

An overlapped amount of the outer circumferential face of the tip sidepin F3 across the step side face 12 b is denoted by an offset width N.When the tip side pin F3 is positioned to have a small portion of theouter circumferential face of the tip side pin F3 disposed across thestep side face 12 b with the flat face F4 of the tip side pin F3 beingpositioned off and above the step bottom face 12 a, as is the case withthis embodiment, the offset amount N should be set to 0<N≤0.5 mm and ispreferably set to 0<N≤0.25 mm.

Since the tip side pin F3 is positioned to have only a small portion ofthe outer circumferential face of the tip side pin F3 disposed acrossthe step side face 12 b in the first primary joining process of thisembodiment, an amount of the first aluminum alloy of the jacket body 2mixing into the sealing body 3 can be kept very small while the firstbutted portion J1 can be reliably joined.

In addition, since the step side face 12 b is in parallel with the outercircumferential face of the tip side pin F3, the overlapped amount ofthe tip side pin F3 across the step side face 12 b is constant in theheight direction. As a result, if the tip side pin is positioned to havea small portion of the outer circumferential face of the tip side pin F3disposed across the step side face 12 b of the peripheral wall stepportion 12, the plastically flowing material is stirred relativelyhomogeneously over the friction-stirred region, which contributes tosuppressing the decrease in the strength of the joined portion.

In addition, since the plastically flowing material is held down by theouter circumferential face of the base side pin F2, as is the case withthe first embodiment, the recessed groove formed on the surface of thejoined portion can be made smaller while the raised portion that can beformed on the side of the recessed groove is not formed or can be madesmaller if it is formed. Furthermore, the surface roughness of thejoined portion is made smaller as well, and the quality of the joinedportion is preferably stabilized.

Third Embodiment

Next, a method for manufacturing a liquid-cooling jacket of a thirdembodiment of the present invention is described. A preparation process,a placing process, a first primary joining process and a second primaryjoining process are performed for the method for manufacturing aliquid-cooling jacket of the third embodiment. The preparation process,the placing process and the second primary joining process in the thirdembodiment are equivalent to corresponding processes in the firstembodiment. The following description focusses on differences from thefirst embodiment.

In the first primary joining process of the third embodiment, as shownin FIG. 16 , friction-stir-welding is performed by moving the primaryjoining rotary tool F along the first butted portion J1 with the outercircumferential face of the tip side pin F3 being kept off the step sideface 12 b and with the flat face F4 of the tip side pin F3 beingpositioned a short length below the step bottom face 12 a.

The third embodiment can provide generally the same effect as the firstembodiment. In addition, since friction-stir-welding is performed withthe flat face F4 of the tip side pin F3 being positioned below the stepbottom face 12 a, the strength of the second butted portion J2 isincreased. Furthermore, since the tip side pin F3 is positioned to haveonly a small tip portion of the tip side pin F3 disposed across the stepbottom face 12 a, the first aluminum alloy of the jacket body 2 can bewell prevented from mixing into the sealing body 3.

Fourth Embodiment

Next, a method for manufacturing a liquid-cooling jacket of a fourthembodiment of the present invention is described. A preparation process,a placing process, a first primary joining process and a second primaryjoining process are performed for the method for manufacturing aliquid-cooling jacket of the fourth embodiment. The preparation process,the placing process and the second primary joining process in the fourthembodiment are equivalent to corresponding processes in the firstembodiment. The following description focusses on differences from thefirst embodiment.

In the first primary joining process of the fourth embodiment as shownin FIG. 17 , friction-stirring is performed with the tip side pin F3being positioned to have a small portion of the outer circumferentialface of the tip side pin F3 disposed across the step side face 12 b andwith the flat face F4 of the tip side pin F3 being positioned a shortlength below the step bottom face 12 a. In the first primary joiningprocess of this embodiment, friction-stirring is performed with thefront face 3 a of the sealing body being held down by the outercircumferential face of the base side pin F2. The offset width N of thetip side pin F3 across the step side face 12 b is set in the same way asin the second embodiment.

The fourth embodiment can provide generally the same effect as thesecond embodiment. In addition, since friction-stirring is performedwith the flat face F4 of the tip side pin F3 being positioned below thestep bottom face 12 a, the joining strength of the second butted portionJ2 is increased. Furthermore, since the flat face F4 is positioned onlya short length below the step bottom face 12 a, the first aluminum alloyof the jacket body 2 can be well prevented from mixing into the sealingbody 3.

Fifth Embodiment

Next, a method for manufacturing a liquid-cooling jacket of a fifthembodiment of the present invention is described. A preparation process,a placing process, a first primary joining process and a second primaryjoining process are performed for the method for manufacturing aliquid-cooling jacket of the fifth embodiment. The preparation process,the placing process and the first primary joining process in the fifthembodiment are equivalent to corresponding processes in the firstembodiment. The following description focusses on differences from thefirst embodiment.

In the second primary joining process of the fifth embodiment as shownin FIG. 18 , friction-stirring is performed with a small portion of thetip side pin F3 being in contact with the step side face 17 b of thesupport pillar step portion 17 and with the flat face F4 of the tip sidepin F3 being positioned off and above the step bottom face 17 a. Thebase side pin F2 is in contact with the front face 3 a of the sealingbody 3 and not in contact with the end face 16 a of the protrudingportion 16. Friction-stirring in the second primary joining process isperformed while the plastically flowing material is being made to flowinto the gap in the third butted portion J3. An overlapped amount of theouter circumferential face of the tip side pin F3 and the step side face17 b may be appropriately set and is preferably set in the same way asthe off-set amount N for the first primary joining process of the secondembodiment (as indicated in FIG. 2 ).

The fifth embodiment can provide approximately the same effects as thefirst embodiment. In addition, since the support pillars 15 are joinedto the sealing body 3 in the second primary joining process of the fifthembodiment, the members are more firmly joined. In addition, since thetip side pin F3 is positioned to have only a small portion of the tipside pin F3 disposed across the step side face 17 b of the supportpillar step portion 17, an amount of the first aluminum alloy of thejacket body 2 mixing into the sealing body 3 can be kept very small. Asa result, the second aluminum alloy is mainly friction-stirred at thethird butted portion J3, which suppresses a decrease in the strength ofthe joined members.

Friction-stirring may be performed with the flat face F4 positioned asmall length across the step bottom face 17 a of the support pillar stepportion 17 in the second primary joining process of the fifthembodiment. That is, in the second primary joining process of thisembodiment, the tip side pin F3 may be positioned to have a smallportion of the tip side pin F3 disposed across the step side face 17 band the flat face F4 may be positioned a small length across the stepbottom face 17 a. As a result, the fourth butted portion J4 can befirmly joined as well while an amount of the first aluminum alloy mixinginto the sealing body 3 from the jacket body 2 can be kept very small.

First Modification Example of the First Embodiment

Next, a method for manufacturing a liquid-cooling jacket of a firstmodification example of the first embodiment is described. As shown inFIG. 19 , the first modification example differs from the firstembodiment in that the provisional joining process, the first primaryjoining process and the second primary joining process are performed inthe first modification example, using a cooling plate. The followingdescription focusses on differences from the first embodiment.

In the first modification example of the first embodiment, the jacketbody 2 is clamped to a table K when a clamping process is performed. Thetable K includes a base plate K1 in a shape of a rectangularparallelepiped, clamps K3 respectively fitted at four corners of thebase plate K1 and a cooling pipe WP that is disposed to run in the baseplate K1. The table K is a member to which the jacket body 2 is clampedand which functions as a “cooling plate” in the claims.

The cooling pipe WP is a pipe member embedded in the base plate K1.Cooling medium flows inside the cooling pipe WP. Though disposition ofthe cooling pipe WP, that is, a shape of a cooling passage through whichthe cooling medium flows, is not specifically limited, the planar shapeof the cooling passage corresponds to the moving track along which thefirst primary joining rotary tool F is moved in the first primaryjoining process in this first modification example. Accordingly, thecooling pipe WP is disposed in a manner that the cooling pipe WP is seenoverlapping roughly with the first butted portion J1 in a plan view.

In the provisional joining process, the first primary joining processand the second primary joining process of the first modificationexample, friction-stir-welding is performed with the cooling mediumflowing in the cooling pipe WP after the jacket body 2 is clamped to thetable K. Thus, friction heat generated by friction-stirring can bedissipated, and deformation of the liquid cooling jacket 1 caused bythermal contraction can be suppressed. In addition, since the coolingpassage is disposed to overlap with the first butted portion J1 (movingtrack along which the provisional joining tool and the primary joiningtool F are moved) in the plan view, a portion where friction heat isgenerated is intensively cooled, which contributes to enhancing coolingefficiency. In addition, since the cooling medium is made to circulatethrough the cooling pipe WP appropriately disposed, it is easy tocontrol the flow of the cooling medium. In addition, the jacket body 2is in face-contact with the table K (cooling plate), which results inthe cooling efficiency being enhanced.

Furthermore, friction-stir-welding may be performed with the coolingmedium being made to flow in the jacket body 2 while the jacket body 2and the sealing body 3 are being cooled with the table K (coolingplate).

Second Modification Example of the First Embodiment

Next, a method for manufacturing a liquid-cooling jacket of a secondmodification example of the first embodiment is described. As shown inFIG. 20A and FIG. 20B, the second modification example differs from thefirst embodiment in that the first primary joining process and thesecond primary joining process are performed in the second modificationexample with both a front face of the jacket body 2 and the front face 3a of the sealing body 3 deforming to curve in a raised shape. Thefollowing description focusses on differences from the first embodiment.

A table KA as shown in FIG. 20A is used for the second modificationexample. The table KA includes a base plate KA1 in a shape of arectangular parallelepiped, a spacer KA2 disposed at a center of thebase plate KA1 and clamps KA3 fitted respectively at four cornerportions of the base plate KA1. The spacer KA2 may be formed integrallywith the base plate KA1 or may be a separate member from the base plateKA1.

In the clamping process of the second modification example, as shown inFIG. 20B, the jacket body 2 and the sealing body 3, which are joinedtogether through the provisional joining process, are clamped to thetable KA with the clamps KA3. There are plasticized regions W formedthrough the provisional joining process.

After the jacket body 2 and the sealing body 3 are clamped to the tableKA, the bottom portion 10 of the jacket body 2, the peripheral wall endface 11 a and the front face 3 a of the sealing body 3 deform to curvein a raised shape with their center portions raised. To be morespecific, a first side portion 21 of a wall portion 11A of the jacketbody 2, a second side portion 22 of a wall portion 11B, a third wallportion 23 of a wall portion 11C and a fourth side portion 24 of a wallportion 11D deform to curve.

In the first and second primary joining processes of the secondmodification example, friction-stir-welding is performed with theprimary joining rotary tool F. In the first primary joining process andthe second primary joining process, a deformation amount of at least oneof the jacket body 2 and the sealing body 3 is measured in advance, andfriction-stir-welding is performed while insertion depths are adjustedaccording to the deformation amount that is measured. Accordingly, theprimary joining rotary tool F is moved along a curved surface of theperipheral wall end face 11 a and the front face 3 a of the sealing body3 in a manner that the moving track along which the primary joiningrotary tool F moves becomes a curved line. As a result, a depth and awidth of the plasticized region are kept constant.

There is a risk that a side of the liquid cooling jacket 1 where thesealing body 3 of the liquid cooling jacket 1 deforms to be in arecessed shape due to thermal contraction of the plasticized regioncaused by input heat generated by friction-stirring. However, accordingto the first primary joining process and the second primary joiningprocess of the second modification example, since the jacket body 2 andthe sealing body 3 are clamped in a raised shape with their centerportions raised so that there remains a tensile stress on each of theperipheral wall end face 11 a and the front face 3 a, the liquid coolingjacket 1 can be made flat after the friction-stir-welding by the thermalcontraction.

In addition, if the primary joining process is performed with aconventional rotary tool, a shoulder portion of the rotary tool comes incontact with the jacket body 2 and the sealing body 3 that curve in araised shape with their center portions raised, which make the operationof the rotary tool difficult. However, the primary joining rotary tool Fof the second modification example does not have a shoulder portion, andhence, there is no problem with the operation of the rotary tool F evenif the jacket body 2 and the sealing body 3 curve in the raised shape

To measure deformations of the jacket body 2 and the sealing body 3, aheight measurement device that has been known may be used. Using afriction-stirring apparatus provided with a measurement device tomeasure at least one of a height of the jacket body 2 from the table KAand a height of the sealing body 3 from the table KA, the first andsecond primary joining processes may be performed while measuring thedeformation amount of the jacket body 2 or the deformation amount of thesealing body 3.

The jacket body 2 and the sealing body 3 are curved so that all of thefirst side portion 21 to the fourth side portion 24 are in a curved lineshape in the second modification example as described above. However,the second modification example is not limited to this. For example, thejacket body 2 and the sealing body 3 may be curved so that the thirdside portion 23 and the fourth side portion 24 are in curved shapeswhile the first side portion 21 and the second side portion 22 arestraight or so that the first side portion 21 and the second sideportion 22 are in curved shapes while the third side portion 23 and thefourth side portion 24 are straight.

In addition, in the second modification example, the height positions ofthe base side pin F2 and the tip side pin F3 are changed according todeformation amounts of the jacket body 2 and the sealing body 3, thefirst and second primary joining processes may be performed while theheights of the base side pin F2 and the tip side pin F3 from the tableKA are kept constant.

In addition, the spacer KA2 may have any shape as long as the front facesides of the jacket body 2 and the sealing body 3 can be clamped in araised shape with their center portions raised. The spacer KA2 may beskipped if the jacket body 2 and the sealing body 3 can be clamped tohave their front face sides raised. Furthermore, the primary joiningrotary tool F may be fitted to a robot arm equipped with a rotationdrive means such as a spindle unit thereon. The rotation axis of theprimary joining rotary tool F can be easily oriented in variousdirections with this configuration.

Third Modification Example of the First Embodiment

Next, a method for manufacturing a liquid-cooling jacket of a thirdmodification example of the first embodiment is described. As shown inFIG. 21 , the third modification example differs from the firstembodiment in that the jacket body 2 and the sealing body 3 are formedin a raised shape with their front face sides being raised in advance inthe preparation process. The following description focusses ondifferences from the first embodiment.

In the preparation process of the third modification example of thefirst embodiment, the jacket body 2 and the sealing body 3 are formedthrough diecasting to be curved in a manner that their front face sidesare in a raised shape. As a result, the jacket body 2 has the bottomportion 10 and the peripheral wall portion 11 in a raised shape withtheir front face sides being raised. The sealing body 3 is curved withthe front face 3 a in the raised shape.

As shown in FIG. 22 , the jacket body 2 and the sealing body 3 that arejoined through the provisional joining are clamped when the clampingprocess is performed. A table KB includes a base plate KB1 in a shape ofa rectangular parallelepiped, a spacer KB2 disposed at a center of thebase plate KB1, clamps KB3 respectively fitted at four corner portionsand a cooling pipe WP disposed to run in the base plate KB1. The tableKB is a member to which the jacket body 2 is clamped and which functionsas a “cooling plate” in the claims.

The spacer KB2 is formed of a curved face KB2 a in a raised shape curvedupward and vertical faces KB2 b, KB2 b formed respectively along bothends of the curved face KB2 a and extending vertically upward from thebase plate KB1. The spacer KB2 has a first side portion Ka and a secondside portion Kb that are in curved shapes and a third side portion Kcand a fourth side portion Kd that are in a straight shape.

The cooling pipe WP is a pipe member embedded in the base plate KB1.Cooling medium flows inside the cooling pipe WP. Though disposition ofthe cooling pipe WP, that is, a shape of a cooling passage through whichthe cooling medium flows, is not specifically limited, the planar shapeof the cooling passage corresponds to the moving track along which theprimary joining rotary tool F is moved in the first primary joiningprocess in this third modification example. Accordingly, the coolingpipe WP is disposed in a manner that the cooling pipe WP is seenoverlapping roughly with the first butted portion J1 in a plan view.

In the clamping process of the third modification example, the jacketbody 2 and the sealing body 3, which are joined together through theprovisional joining process, are clamped to the table KB with the clampsKB3. To be more specific, the jacket body 2 and the sealing body 3 thatare joined together are clamped to the table KB in a manner that a backface of the bottom portion 10 of the jacket body 2 is in face-contactwith the curved face KB2 a. After the jacket body 2 is clamped to thetable KB, the jacket body 2 curves in a manner that the jacket body hasthe first side portion 21 of a wall portion 11A and the second sideportion 22 of a wall portion 11B that are curved lines while the jacketbody has the third side portion 23 of a wall portion 11C and the fourthside portion 24 of a wall portion 11D that are straight lines.

In the first and second primary joining processes of the thirdmodification example, friction-stir-welding is performed with theprimary joining rotary tool F. A deformation amount of at least one ofthe jacket body 2 and the sealing body 3 is measured in advance, andfriction-stir-welding is performed in the first primary joining processand the second primary joining process while insertion depths of thebase side pin F2 and the tip side pin F3 are adjusted according to thedeformation amount that is measured. Accordingly, the primary joiningrotary tool F is made to move along a curved surface of the peripheralwall end faces 11 a and the front face 3 a of the sealing body 3 in amanner that the moving track along which the primary joining rotary toolF moves becomes a curved line or a straight line. As a result, a depthand a width of the plasticized region are kept constant.

There is a risk that a side of the liquid cooling jacket 1 where thesealing body 3 of the liquid cooling jacket 1 deforms to be in arecessed shape due to contraction of the plasticized region caused byinput heat generated by friction-stirring. However, according to thefirst primary joining process and the second primary joining process ofthe third modification example, since the jacket body 2 and the sealingbody 3 are formed in a raised shape in advance so that the liquidcooling jacket 1 can be made flat after the friction-stir-welding by thethermal contraction.

In the third modification example, the back face of the bottom portion10 of the jacket body 2, which is in a recessed shape, is made to be inface-contact with the curved face KB2 a of the spacer KB2. Thus,friction-stir-welding is performed while the jacket body 2 and thesealing body 3 are more efficiently cooled. Since friction heatgenerated by friction-stirring is dissipated, deformation of the liquidcooling jacket 1 caused by thermal contraction can be suppressed. As aresult, the curvatures of the jacket body 2 and the sealing body 3,which are formed in raised shapes, can be made smaller in thepreparation process.

Deformation amounts of the jacket body 2 and the sealing body 3 can bemeasured with a height measurement device that has been known. Forexample, the primary joining process may be performed while measuring adeformation amount of the jacket body 2 or the sealing body 3 by using afriction-stirring apparatus provided with a measurement device tomeasure at least one of a height of the jacket body 2 from the table KBand a height of the sealing body 3 from the table KB.

In the third modification example, the jacket body 2 and the sealingbody 3 are curved in a manner that the first side portion 21 and thesecond side portion 22 are in curved shapes. However otherconfigurations are possible. For example, the spacer KB2 may have aspherical face, and the back face of the bottom portion 10 of the jacketbody 2 may be made to be in face-contact with the spherical face. Inthis case, all of the first side portion 21 to the fourth side portion24 are in curved shapes with the jacket body 2 being clamped to thetable KB.

In the third modification example, the height of the base side pin F2and the tip side pin F3 is altered in accordance with the deformationamounts of the jacket body 2 and the sealing body 3. However, theprimary joining process may be performed with the heights of the baseside pin F2 and the tip side pin F3 from the table KB being keptconstant.

BRIEF DESCRIPTION OF SIGNS

-   -   1 Liquid cooling jacket    -   2 Jacket body    -   3 Sealing body    -   3 a Front face    -   3 b Back face    -   3 c Outer peripheral side face    -   10 Bottom face    -   11 Peripheral wall portion    -   11 a Peripheral wall end face    -   12 Peripheral wall step portion    -   12 a Step bottom face    -   12 b Step side face    -   13 Recessed portion    -   15 Support pillar    -   16 Protruding portion    -   F Primary joining rotary tool (Rotary tool)    -   F1 Base shaft portion    -   F2 Base side pin    -   F3 Tip side pin    -   F4 Flat face    -   J1 First butted portion    -   J2 Second butted portion    -   J3 Third butted portion    -   J4 Fourth butted portion    -   K Table (Cooling plate)    -   W1 Plasticized region    -   W2 Plasticized region    -   WP Cooling pipe

What is claimed is:
 1. A method for manufacturing a liquid coolingjacket joining a jacket body and a sealing body throughfriction-stirring, wherein the jacket body includes a bottom portion, aperipheral wall portion extending upward from a peripheral edge of thebottom portion and a support pillar extending upward from the bottomportion, and is made of a first aluminum alloy, the sealing bodyincludes a hole portion into which a tip portion of the support pillaris inserted, seals an opening of the jacket body, and is made of asecond aluminum alloy, the first aluminum alloy has a higher hardnessthan a hardness of the second aluminum alloy, a rotary tool is a rotarytool for primary joining for the friction stirring and includes a baseside pin and a tip side pin, the base side pin has a taper angle largerthan that of the tip side pin, and the rotary tool includes a pin stepportion formed with a stair shaped cross section on an outercircumferential face of the base side pin, the method comprising: apreparation process of forming a peripheral wall step portion along aninner peripheral edge of the peripheral wall portion, the peripheralwall step portion including a step bottom face and a step side faceextending upward toward the opening of the jacket body from the stepbottom face and forming a support pillar step portion at the tip portionof the support pillar, the support pillar step portion including a stepbottom face and a step side face extending diagonally upward from thestep bottom face in a way that the tip portion of the support pillartapers to become thinner toward a tip end of the tip portion, wherein aplate thickness of the sealing body is larger than a height of the stepside face of the support pillar step portion; a placing process ofplacing the sealing body on the jacket body to form a first buttedportion, a second butted portion, a third butted portion and a fourthbutted portion, the first butted portion where the step side face of theperipheral wall step portion and an outer peripheral side face of thesealing body butt each other, the second butted portion where a backface of the sealing body is placed on the step bottom face of theperipheral wall step portion, the third butted portion where the stepside face of the support pillar portion and a hole wall of the holeportion of the sealing body portion butt each other with a gap presentbetween the step side face of the support pillar portion and the holewall, the fourth butted portion where the back face of the sealing bodyis placed on the step bottom face of the support pillar step bottomface; and a second primary joining process of friction-stirring beingperformed by inserting the tip side pin and the base side pin of therotary tool that is rotating into the sealing body and moving the rotarytool along the third butted portion with the outer circumferential faceof the base side pin being in contact with a front face of the sealingbody and with an outer circumferential face of the tip side pin beingkept off the step side face of the support pillar step portion whilehaving the second aluminum alloy of the sealing body flow into the gap.2. The method for manufacturing a liquid cooling jacket as claimed inclaim 1, wherein the friction-stirring in the second primary joiningprocess is performed by moving the rotary tool along the third buttedportion with the tip side pin being slightly in contact with the stepbottom face of the support pillar step portion.
 3. A method formanufacturing a liquid cooling jacket joining a jacket body and asealing body through friction-stirring, wherein the jacket body includesa bottom portion, a peripheral wall portion extending upward from aperipheral edge of the bottom portion and a support pillar extendingupward from the bottom portion, and is made of a first aluminum alloy,the sealing body includes a hole portion into which a tip portion of thesupport pillar is inserted, seals an opening of the jacket body and ismade of a second aluminum alloy, the first aluminum alloy has a higherhardness than a hardness of the second aluminum alloy, a rotary tool isa rotary tool for primary joining for the friction stirring and includesa base side pin and a tip side pin, the base side pin has a taper anglelarger than that of the tip side pin, and the rotary tool includes a pinstep portion formed with a stair shaped cross section on an outercircumferential face of the base side pin, the method comprising: apreparation process of forming a peripheral wall step portion along aninner peripheral edge of the peripheral wall portion, the peripheralwall step portion including a step bottom face and a step side faceextending upward toward the opening of the jacket body from the stepbottom face and forming a support pillar step portion at the tip portionof the support pillar, the support pillar step portion including a stepbottom face and a step side face extending diagonally upward from thestep bottom face in a way that the tip portion of the support pillartapers to become thinner toward a tip end of the tip portion, wherein aplate thickness of the sealing body is larger than a height of the stepside face of the support pillar step portion; a placing process ofplacing the sealing body on the jacket body to form a first buttedportion, a second butted portion, a third butted portion and a fourthbutted portion, the first butted portion where the step side face of theperipheral wall step portion and an outer peripheral side face of thesealing body butt each other, the second butted portion where a backface of the sealing body is placed on the step bottom face of theperipheral wall step portion, the third butted portion where the stepside face of the support pillar portion and a hole wall of the holeportion of the sealing body portion butt each other with a gap presentbetween the step side face of the support pillar portion and the holewall, the fourth butted portion where the back face of the sealing bodyis placed on the step bottom face of the support pillar step bottomface; and a second primary joining process of friction-stirring beingperformed by inserting the tip side pin and the base side pin of therotary tool that is rotating into the sealing body and moving the rotarytool along the third butted portion with the outer circumferential faceof the base side pin being in contact with a front face of the sealingbody and with an outer circumferential face of the tip side pin beingslightly in contact with the step side face of the support pillar stepportion while having the second aluminum alloy of the sealing body flowinto the gap.
 4. The method for manufacturing a liquid cooling jacket asclaimed in claim 3, wherein the friction-stirring in the second primaryjoining process is performed by moving the rotary tool along the thirdbutted portion with the tip side pin being slightly in contact with thestep bottom face of the support pillar step portion.
 5. The method formanufacturing a liquid cooling jacket as claimed in claim 1, wherein inthe second primary joining process, the friction-stirring is performedby moving the rotary tool along the third butted portion and making oneround around the support pillar step portion.
 6. The method formanufacturing a liquid cooling as claimed in claim 1, further comprisinga first primary joining process of friction-stirring on the first buttedportion by moving the rotary tool one round along the first buttedportion.
 7. The method for manufacturing a liquid cooling jacket asclaimed in claim 6, wherein in the preparation process, the jacket bodyis formed through die-casting, the bottom portion of the jacket body isformed in a raised shape with a front face of the bottom portion beingraised and the sealing body is formed in a raised shape with a frontface of the sealing body being raised.
 8. The method for manufacturing aliquid cooling jacket as claimed in claim 7, wherein a deformationamount of the jacket body is measured in advance and thefriction-stirring is performed while an insertion depth of the base sidepin and the tip side pin of the rotary tool is being adjusted inaccordance with the deformation amount in the first primary joiningprocess.
 9. The method for manufacturing a liquid cooling jacket asclaimed in claim 6, further comprising a provisional joining process toprovisionally join the first butted portion prior to the first primaryjoining process.
 10. The method for manufacturing a liquid coolingjacket as claimed in claim 6, wherein in the first primary joiningprocess, a cooling plate in which a cooling medium flows is fixed on aback face of the bottom portion and the friction-stirring is performedwhile the jacket body and the sealing body are being cooled by thecooling plate.
 11. The method for manufacturing a liquid cooling jacketas claimed in claim 10, wherein a front face of the cooling plate ismade to be in face-contact with the back face of the bottom portion. 12.The method for manufacturing a liquid cooling jacket as claimed in claim10, wherein the cooling plate includes a cooling passage through whichthe cooling medium flows and the cooling passage has a planar shape thatcorresponds to a moving track along which the rotary tool moves in theprimary joining process.
 13. The method for manufacturing a liquidcooling jacket as claimed in claim 10, wherein the cooling passagethrough which the cooling medium flows is constituted by a cooling pipethat is embedded in the cooling plate.
 14. The method for manufacturinga liquid cooling jacket as claimed in claim 6, wherein in the firstprimary joining process, the friction-stirring is performed while thejacket body and the sealing body are being cooled by a cooling mediumbeing made to flow in a hollow portion formed by the jacket body and thesealing body.
 15. The method for manufacturing a liquid cooling jacketas claimed in claim 3, wherein in the second primary joining process,the friction-stirring is performed by moving the rotary tool along thethird butted portion and making one round around the support pillar stepportion.
 16. The method for manufacturing a liquid cooling as claimed inclaim 3, further comprising a first primary joining process offriction-stirring on the first butted portion by moving the rotary toolone round along the first butted portion.